Semiconductor Module

Abstract

The electrical resistance between the semiconductor unit and the plurality of connection terminals is reduced while suppressing stress concentration at the joints. [Solution] The semiconductor module 100 comprises a semiconductor unit 40 including a mounting substrate 41 and a semiconductor chip 45 mounted on the mounting substrate 41, a storage case 10 that houses the semiconductor unit 40, a plurality of connection terminals 20 mounted on the storage case 10, and connection leads 60 that electrically connect the semiconductor unit 40 and the plurality of connection terminals 20, the connection leads 60 being made of a conductive plate material and including a first connection portion 61 joined to the plurality of connection terminals 20, a second connection portion 62 joined to the semiconductor unit 40 at a position lower than the first connection portion 61 in the thickness direction of the mounting substrate 41, and a connecting portion 63 that connects the first connection portion 61 and the second connection portion 62, and the connecting portion 63 includes a portion that is inclined with respect to the thickness direction of the mounting substrate 41.

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor module. [Background technology]

[0002] Semiconductor modules have been proposed in the past, each equipped with a semiconductor chip such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). In the semiconductor module, connection terminals for external connection are electrically connected to the semiconductor chip by linear bonding wires or band-like ribbon wires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-336043 [Patent Document 2] U.S. Patent No. 5,753,971 [Patent Document 3] Special Publication No. 2015-530748 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-131592 [Patent Document 5] Japanese Patent Application Laid-Open No. 2000-106416 [Patent Document 6] Japanese Patent Application Laid-Open No. 2012-094713 [Patent Document 7] Japanese Patent Application Laid-Open No. 2008-252055 [Patent Document 8] Japanese Patent Application Publication No. 2017-092388 [Patent Document 9] Japanese Patent Application Publication No. 7-079067 [Patent Document 10] Japanese Patent Application Publication No. 4-284968 [Patent Document 11] Japanese Patent Application Publication No. 7-116835 [Patent Document 12] Japanese Patent Application Publication No. 4-123867 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a trend toward increased current capacity for semiconductor modules. However, with conventional bonding wires or ribbon wires, the expansion of their cross-sectional area is limited due to constraints on bonding techniques such as ultrasonic bonding, making it difficult to sufficiently reduce electrical resistance. On the other hand, the use of plate-shaped conductors with sufficient cross-sectional area makes it possible to reduce electrical resistance. However, there is a possibility that local stress may concentrate at the joint due to displacement of the connection object. In consideration of the above circumstances, one aspect of the present disclosure aims to reduce the electrical resistance between a semiconductor unit and multiple connection terminals while suppressing stress concentration at the joint. [Means for solving the problem]

[0005] In order to solve the above problems, a semiconductor module according to one embodiment of the present disclosure comprises a semiconductor unit including a mounting substrate and a semiconductor chip mounted on the mounting substrate, a storage case for accommodating the semiconductor unit, a plurality of connection terminals mounted on the storage case, and connection leads for electrically connecting the semiconductor unit and the plurality of connection terminals, wherein the connection leads are made of a conductive plate material and include a first connection portion joined to the plurality of connection terminals, a second connection portion joined to the semiconductor unit at a position lower than the first connection portion in the plate thickness direction of the mounting substrate, and a connecting portion for connecting the first connection portion and the second connection portion, and the connecting portion includes a portion inclined with respect to the plate thickness direction. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view of a semiconductor module according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. [Figure 4] FIG. 2 is a plan view focusing on a first connection portion of a connection lead. [Figure 5] 10A and 10B are explanatory diagrams of a process for installing a connection lead. [Figure 6] FIG. 10 is a perspective view of a connection lead in a second embodiment. [Figure 7] FIG. 10 is a perspective view of a connection lead according to a modified example. [Figure 8] FIG. 10 is a perspective view of a connection lead according to a modified example. [Figure 9] FIG. 10 is a perspective view of a connection lead according to a modified example. [Figure 10] FIG. 10 is a perspective view of a connection lead according to a modified example. [Figure 11] FIG. 10 is a perspective view of a connection lead according to a modified example. [Figure 12] FIG. 10 is a cross-sectional view of a connection lead according to a modified example. [Figure 13] FIG. 10 is a cross-sectional view of a connection lead according to a modified example. [Figure 14] FIG. 10 is a cross-sectional view of a connection lead according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0007] The embodiments for carrying out the present disclosure will be described with reference to the drawings. Note that the dimensions and scale of each element in each drawing may differ from those of the actual product. Furthermore, the embodiment described below is an exemplary embodiment that may be envisioned when carrying out the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiment exemplified below.

[0008] A: First embodiment Fig. 1 is a plan view of a semiconductor module 100 according to a first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. The semiconductor module 100 according to this embodiment is a power semiconductor module used in a power conversion device such as a three-phase inverter circuit. Specifically, the semiconductor module 100 constitutes a half-bridge circuit corresponding to one phase of the power conversion device.

[0009] In the following explanation, three mutually orthogonal axes (X-axis, Y-axis, and Z-axis) are assumed. The direction along the X-axis (X1 direction and X2 direction) is referred to as the "X direction." Similarly, the direction along the Y-axis (Y1 direction and Y2 direction) is referred to as the "Y direction," and the direction along the Z-axis (Z1 direction and Z2 direction) is referred to as the "Z direction."

[0010] In actual use, the semiconductor module 100 may be installed in any direction, but for convenience in the following description, the Z1 direction is assumed to be upward and the Z2 direction is assumed to be downward. Therefore, the surface of any element of the semiconductor module 100 facing the Z1 direction may be referred to as the "top surface," and the surface of the element facing the Z2 direction may be referred to as the "bottom surface." In addition, in the following description, observing any element of the semiconductor module 100 from a line of sight along the Z direction is referred to as a "planar view."

[0011] As illustrated in FIGS. 1 and 2, the semiconductor module 100 includes a housing case 10, a plurality of connection terminals 20, a heat sink 30, a semiconductor unit 40, a plurality of connection wires 50, and a plurality of connection leads 60.

[0012] The accommodating case 10 is a structure formed in a rectangular frame shape in a plan view, and accommodates the semiconductor unit 40. That is, the semiconductor unit 40 is located inside the accommodating case 10 in a plan view. The space inside the accommodating case 10 is filled with a sealing resin (not shown) for sealing the semiconductor unit 40. The accommodating case 10 is formed from various insulating resins, such as PPS (polyphenylene sulfide) resin, PBT (polybutylene terephthalate) resin, PBS (polybutylene succinate) resin, PA (polyamide) resin, or ABS (acrylonitrile-butadiene-styrene) resin. However, the material of the accommodating case 10 is not limited to the above examples.

[0013] The storage case 10 includes a side wall 11 and a protrusion 12. The side wall 11 is a wall-like portion formed in a rectangular frame shape in a plan view. The protrusion 12 is a rectangular frame-like portion that protrudes inward from the inner wall surface of the side wall 11. The "inward" of the inner wall surface is the direction toward the center of the storage case 10 in a plan view. In other words, the protrusion 12 is located inside the side wall 11 in a plan view. As illustrated in FIG. 2 , the upper surface of the protrusion 12 facing the Z1 direction (hereinafter referred to as the "terminal surface 14") is located in the Z2 direction relative to the upper surface of the side wall 11 facing the Z1 direction (hereinafter referred to as the "top surface 15"). In other words, the terminal surface 14 of the protrusion 12 is located lower than the top surface 15 of the side wall 11. The storage case 10 has a plurality of installation holes 13 formed along the side wall 11. Each of the plurality of installation holes 13 is a through-hole that communicates from the top surface 15 of the side wall portion 11 to the terminal surface 14 of the protrusion portion 12 .

[0014] The multiple connection terminals 20 are conductive members installed in the casing 10 and are external terminals for electrically connecting the semiconductor unit 40 to an external device (not shown). Each connection terminal 20 is formed of a low-resistance conductive material such as copper or a copper alloy. The connection terminals 20 are selectively inserted into some of the multiple installation holes 13. With the above configuration, the positions or total number of the connection terminals 20 can be appropriately changed depending on, for example, the structure of a wiring board externally attached to the semiconductor module 100 or the structure of the semiconductor unit 40. Note that the connection terminals 20 are shaded in FIG. 1 for convenience.

[0015] 2, each of the multiple connection terminals 20 includes a first portion 21 and a second portion 22. The first portion 21 is a pad-like portion installed on the terminal surface 14 of the protrusion 12. On the other hand, the second portion 22 is a portion of the connection terminal 20 that extends linearly in the Z direction. That is, the second portion 22 extends in the Z direction from the first portion 21 to pass through the inside of the side wall portion 11 (the installation hole 13), and the end portion located in the Z1 direction protrudes from the top surface 15 of the side wall portion 11. As described above, each connection terminal 20 is formed in an L-shape when viewed from the side.

[0016] The plurality of connection terminals 20 include a plurality of power supply terminals 20a, a plurality of output terminals 20b, a plurality of power supply terminals 20c, and a plurality of control terminals 20g. The plurality of power supply terminals 20a are connection terminals 20 (P terminals) to which a high-level power supply potential is supplied from a power supply device (not shown). The plurality of power supply terminals 20c are connection terminals 20 (N terminals) to which a low-level power supply potential is supplied from the power supply device. The plurality of output terminals 20b are connection terminals 20 for outputting power to load devices such as electric motors. The plurality of control terminals 20g are connection terminals 20 to which a control signal for controlling the semiconductor unit 40 is supplied from a drive device (not shown).

[0017] 2 is a rectangular substrate on which the semiconductor unit 40 is mounted, and is disposed so as to close the opening of the casing 10. Specifically, the semiconductor unit 40 is disposed on the upper surface of the heat sink 30. The heat sink 30 is formed of a metal material with high thermal conductivity, such as aluminum or copper, and functions as a cooler that radiates heat generated in the semiconductor unit 40. The heat sink 30 may also be used as a ground body that is set to a ground potential.

[0018] The semiconductor unit 40 includes a mounting substrate 41 and multiple semiconductor chips 45 (45a, 45b). The multiple semiconductor chips 45 are mounted on the mounting substrate 41. The mounting substrate 41 is a wiring substrate such as a DCB (Direct Copper Bonding) substrate, an AMB (Active Metal Brazing) substrate, or an IMS (Insulated Metal Substrate). The Z direction (Z1 direction, Z2 direction) corresponds to the thickness direction of the mounting substrate 41, and the X direction (X1 direction, X2 direction) and the Y direction (Y1 direction, Y2 direction) correspond to the in-plane directions of the mounting substrate 41.

[0019] The mounting substrate 41 is formed by laminating an insulating substrate 42, a metal layer 43, and a plurality of conductive patterns 44 (44a, 44b, 44c). The insulating substrate 42 is a rectangular plate-like member made of an insulating material. The insulating substrate 42 is made of a ceramic material such as aluminum oxide, aluminum nitride, or silicon nitride, or a resin material such as epoxy resin. The metal layer 43 is a thin plate-like conductor bonded to the lower surface of the insulating substrate 42. The metal layer 43 is made of a metal material with high thermal conductivity such as copper or aluminum, and transfers heat generated in the semiconductor unit 40 to the heat sink 30.

[0020] Each of the plurality of conductive patterns 44 is a thin plate-like conductor placed on the upper surface of the insulating substrate 42. Each conductive pattern 44 is formed from a low-resistance conductive material such as copper or a copper alloy. The plurality of conductive patterns are formed on the upper surface of the insulating substrate 42 so as to be spaced apart from each other in a plan view.

[0021] 1, the multiple conductive patterns 44 include a conductive pattern 44a, a conductive pattern 44b, and a conductive pattern 44c. The conductive patterns 44b and 44c are located in the Y2 direction of the conductive pattern 44a in a planar view. The multiple power supply terminals 20a are located in the X1 direction of the conductive pattern 44a in a planar view. The conductive pattern 44c is located in the X1 direction of the conductive pattern 44b in a planar view. The multiple output terminals 20b are located in the X2 direction of the conductive pattern 44b in a planar view. Furthermore, the multiple power supply terminals 20c are located in the X1 direction of the conductive pattern 44c in a planar view.

[0022] Each semiconductor chip 45 is a power semiconductor element mounted on the mounting substrate 41, and is mounted on the mounting substrate 41 with a conductive bonding material (not shown), such as solder or conductive paste. Specifically, the semiconductor chip 45a is bonded to the conductive pattern 44a, and the semiconductor chip 45b is bonded to the conductive pattern 44b.

[0023] Each semiconductor chip 45 is a switching element that switches current conduction / cutoff. Semiconductor chip 45a constitutes the upper arm of the power conversion device, and semiconductor chip 45b constitutes the lower arm of the power conversion device. Each semiconductor chip 45 is, for example, an RC (Reverse Conductive)-IGBT in which an IGBT (Insulated Gate Bipolar Transistor) and an FWD (Free Wheeling Diode) are connected in anti-parallel. Each semiconductor chip 45 includes a main electrode C, a main electrode E, and a control electrode G. The main electrode C is a collector electrode that constitutes the lower surface of the semiconductor chip 45, and the main electrode E is an emitter electrode that constitutes the upper surface of the semiconductor chip 45. The control electrode G is a gate electrode to which a control signal is supplied from a drive device, and together with the main electrode E, constitutes the upper surface of the semiconductor chip 45.

[0024] The main electrode E of the semiconductor chip 45a is electrically connected to the conductive pattern 44b by a plurality of connecting wires 50. The main electrode E of the semiconductor chip 45b is electrically connected to the conductive pattern 44c by a plurality of connecting wires 50. The control electrode G of the semiconductor chip 45a is electrically connected to one control terminal 20g by one connecting wire 50, and the control electrode G of the semiconductor chip 45b is electrically connected to one control terminal 20g by one connecting wire 50. Note that the control electrode G of each semiconductor chip 45 may be connected to multiple control terminals 20g by different connecting wires 50.

[0025] Each of the multiple connection leads 60 (60a, 60b, 60c) is a conductive member for electrically connecting the semiconductor unit 40 and the multiple connection terminals 20. That is, the semiconductor unit 40 is electrically connected to an external device (e.g., a power supply device or a load device) via the connection leads 60 and the connection terminals 20. The connection lead 60a electrically connects the multiple power supply terminals 20a and the conductive pattern 44a. The connection lead 60b electrically connects the multiple output terminals 20b and the conductive pattern 44b. The connection lead 60c electrically connects the multiple power supply terminals 20c and the conductive pattern 44c.

[0026] Each connection lead 60 is made of a low-resistance conductive material such as copper or a copper alloy. Each connection lead 60 is made of a conductive plate material. Specifically, each connection lead 60 is integrally formed by pressing a single conductive plate. The rigidity of the connection lead 60 exceeds the rigidity of the connection wire 50. In other words, the connection wire 50 is a flexible wiring member formed in a linear shape, while the connection lead 60 is a hard wiring member formed in a plate shape. Note that each connection lead 60 may be made by connecting multiple plate materials formed separately from each other.

[0027] FIG. 3 is a perspective view of the connection lead 60c. As illustrated in FIGS. 1 to 3, the connection lead 60c includes a first connection portion 61, a second connection portion 62, and a linking portion 63. For example, the first connection portion 61, the second connection portion 62, and the linking portion 63 are integrally formed by pressing a strip-shaped metal plate of a predetermined width in two positions in the longitudinal direction in opposite directions. The first connection portion 61 is a portion that constitutes the end of the connection lead 60c in the Z1 direction. The second connection portion 62 is a portion that constitutes the end of the connection lead 60c in the Z2 direction. The linking portion 63 is a portion that connects the first connection portion 61 and the second connection portion 62.

[0028] The first connection portion 61 and the second connection portion 62 are each a flat portion of the connection lead 60c that is parallel to the XY plane. The first connection portion 61 and the second connection portion 62 are located at different positions in the Z direction. Specifically, the second connection portion 62 is located in the Z2 direction relative to the first connection portion 61. As can be seen from FIGS. 2 and 3, the first connection portion 61 and the second connection portion 62 include portions that face each other with a gap in between in the Z direction.

[0029] As illustrated in FIG. 3 , the connecting portion 63 is a plate-like portion that spans an edge 611 of the first connecting portion 61 that is located inside the housing case 10 in a plan view and an edge 621 of the second connecting portion 62 that is located outside the housing case 10. The edge 611 of the first connecting portion 61 is a periphery of the first connecting portion 61 that is located in the X2 direction. The edge 621 of the second connecting portion 62 is a periphery of the second connecting portion 62 that is located in the X1 direction. In other words, the connecting portion 63 connects edges that are located on opposite sides of the first connecting portion 61 and the second connecting portion 62. The X2 direction is an example of a "first direction," and the X1 direction is an example of a "second direction."

[0030] The connecting portion 63 is a plate-like portion inclined at a predetermined angle with respect to the Z direction (the plate thickness direction of the mounting substrate 41). Specifically, the connecting portion 63 is inclined outward from the casing 10 from the edge 611 of the first connecting portion 61 to the edge 621 of the second connecting portion 62. That is, the connecting portion 63 is inclined in the X1 direction from the first connecting portion 61 to the second connecting portion 62. Therefore, the connection lead 60 is formed in a Z-shape in a side view. The angle θ of the connecting portion 63 with respect to the first connecting portion 61 and the second connecting portion 62 is set to an appropriate value within a range of, for example, 10° or more (more preferably 30° or more) and 80° or less (more preferably 60° or less).

[0031] 1 and 2, the first connection portion 61 of the connection lead 60c is joined to the multiple power terminals 20c. That is, the multiple power terminals 20c are connected in parallel to the first connection portion 61. Specifically, the first connection portion 61 is joined to the first portion 21 of each of the multiple power terminals 20c. That is, the first connection portion 61 is arranged to overlap the multiple power terminals 20c in a plan view, and the surface of the first connection portion 61 in the Z2 direction is joined to each power terminal 20c (terminal surface 14) by, for example, solder 55a. The first connection portion 61 is supported by the terminal surface 14 of the accommodating case 10. As described above, in the first embodiment, the first portion 21 of each connection terminal 20 is disposed on the upper surface (terminal surface 14) of the protruding portion 12 of the accommodating case 10. Therefore, the first connection portion 61 of the connection lead 60 joined to the first portion 21 can be effectively supported by the protruding portion 12.

[0032] The second connection portion 62 of the connection lead 60c is joined to the conductive pattern 44c of the mounting board 41. Specifically, the surface of the second connection portion 62 facing in the Z2 direction is joined to the conductive pattern 44c by, for example, solder 55b. In other words, the second connection portion 62 is supported by the mounting board 41. As can be understood from the above description, the second connection portion 62 is joined to the conductive pattern 44c at a position lower in the Z direction than the first connection portion 61 (a position closer to the mounting board 41).

[0033] 4 is a plan view focusing on the first connection portion 61 of the connection lead 60c. As illustrated in FIGS. 3 and 4, a plurality of recesses 64 are formed in an edge 612 of the first connection portion 61 located in the X1 direction. Each recess 64 is a slit that penetrates the first connection portion 61 in the plate thickness direction (Z direction) and extends linearly from the edge 612 in the X2 direction. The plurality of recesses 64 are formed at intervals from one another in the Y direction.

[0034] 4, the first connection portion 61 overlaps with the multiple power supply terminals 20c in plan view. Specifically, the first connection portion 61 overlaps with the first portion 21 of the power supply terminal 20c in plan view. Each recess 64 overlaps with the gap between two power supply terminals 20c that are adjacent to each other in the Y direction among the multiple power supply terminals 20c in plan view.

[0035] Although the above description has focused on the connection lead 60c for convenience, the connection leads 60a and 60b have the same configuration. Specifically, the connection lead 60a includes a first connection portion 61 joined to the multiple power supply terminals 20a, a second connection portion 62 joined to the conductive pattern 44a of the semiconductor unit 40, and a linking portion 63 that links the first connection portion 61 and the second connection portion 62. The connection lead 60b includes the first connection portion 61 joined to the multiple output terminals 20b, the second connection portion 62 joined to the conductive pattern 44b of the semiconductor unit 40, and the linking portion 63 that links the first connection portion 61 and the second connection portion 62.

[0036] As described above, in the first embodiment, the semiconductor unit 40 and the plurality of connection terminals 20 are electrically connected using connection leads 60 made of a conductive plate material, rather than using connection wires 50 for each connection terminal 20. With the above configuration, a sufficient cross-sectional area of ​​the current path is ensured compared to a configuration in which connection wires 50 are used, and therefore the electrical resistance between the semiconductor unit 40 and the plurality of connection terminals 20 is reduced, resulting in reduced heat generation.

[0037] Note that the distance between the semiconductor unit 40 and each connection terminal 20 may vary due to manufacturing errors or thermal deformation of the semiconductor module 100. For example, in a configuration in which the coupling portion 63 extends parallel to the Z direction (hereinafter referred to as the "comparative example"), the spacing between the first connection portion 61 and the second connection portion 62 does not change, and therefore stress caused by variations in the distance between the semiconductor unit 40 and each connection terminal 20 may concentrate at the junction between the first connection portion 61 and each connection terminal 20 or the junction between the second connection portion 62 and the semiconductor unit 40. In contrast to the comparative example, in the first embodiment, the coupling portion 63 of the connection lead 60 includes a portion that is inclined with respect to the Z direction, and therefore the coupling portion 63 elastically deforms relative to the first connection portion 61 and the second connection portion 62. That is, the connection lead 60 is elastically deformable such that the spacing between the first connection portion 61 and the second connection portion 62 varies depending on the angle θ of the coupling portion 63. According to the above configuration, stress caused by fluctuations in the distance between the semiconductor unit 40 and the plurality of connection terminals 20 is absorbed by elastic deformation of the connection leads 60. Therefore, stress concentration at the joints between the first connection portion 61 and each connection terminal 20 or the joints between the second connection portion 62 and the semiconductor unit 40 can be suppressed.

[0038] In particular, in the first embodiment, the linking portion 63 is a plate-like portion that spans an edge 611 of the first connecting portion 61 and an edge 621 of the second connecting portion 62. According to the above configuration, the distance between the first connecting portion 61 and the second connecting portion 62 in the Z direction and the distance between the first connecting portion 61 and the second connecting portion 62 in the X direction (the in-plane direction of the mounting substrate 41) change due to elastic deformation of the connection lead 60. Therefore, the connection lead 60 can absorb both stress caused by fluctuations in the distance between the semiconductor unit 40 and each connection terminal 20 in the plate thickness direction and stress caused by fluctuations in the distance between the semiconductor unit 40 and each connection terminal 20 in the in-plane direction. Furthermore, the first connecting portion 61 and the second connecting portion 62 include portions where they face each other, and the opposite edges (611, 621) of the first connecting portion 61 and the second connecting portion 62 are connected to each other by the linking portion 63. Therefore, the planar space required for installing the connection leads 60 can be reduced.

[0039] 5 is an explanatory diagram of the process of installing the connection lead 60c. The process of installing the connection lead 60c includes a preparation step P1, a holding step P2, a transport step P3, and a joining step P4.

[0040] In the preparation step P1, solid solder 55a and solder 55b are applied. Specifically, solder 55a is applied to the surfaces (terminal surfaces 14) of the plurality of power supply terminals 20c, and solder 55b is applied to the surface of the conductive pattern 44b.

[0041] In a holding step P2 after the preparation step P1, the connection lead 60c is held by a holder 70. The holder 70 is a jig for holding the connection lead 60c. The holder 70 is, for example, a suction tube that holds the connection lead 60c by suction to the first connection portion 61, and is made of, for example, a metal material with high thermal conductivity. In the holding step P2, the holder 70 is heated. The connection lead 60c is also heated by the heat transferred from the holder 70. The connection lead 60c is heated to a temperature above the melting points of the solders 55a and 55b.

[0042] In the transport step P3 after the holding step P2, the holder 70 holding the connection lead 60c moves, transporting the connection lead 60c to a target position. Specifically, the connection lead 60c is transported so that the first connection portion 61 contacts the solder 55a and the second connection portion 62 contacts the solder 55b. As described above, since the connection lead 60c is in a heated state, in the transport step P3, the contact of the first connection portion 61 melts the solder 55a, and the contact of the second connection portion 62 melts the solder 55b.

[0043] After the transfer step P3, the connection leads 60c are joined in a joining step P4. Specifically, in the joining step P4, the connection leads 60c are released from the holder 70 and removed. This ends the heating of the connection leads 60c, and the solders 55a and 55b cool and harden. The hardening of the solders 55a joins the first connection portions 61 to the power terminals 20c, and the hardening of the solders 55b joins the second connection portions 62 to the conductive pattern 44c.

[0044] The process of installing the connection lead 60c is achieved by the above procedure. Note that, although the above description has focused on the installation of the connection lead 60c for the sake of convenience, the connection leads 60a and 60b are also installed by the same procedure.

[0045] As described above, in the first embodiment, the first connection portion 61 and each connection terminal 20, and the second connection portion 62 and the semiconductor unit 40 can be easily joined by the solder 55 (55a, 55b). For example, the temperature required for joining can be reduced compared to joining by melting the connection leads 60 (e.g., laser welding). Note that any method can be used to join the connection leads 60 to the connection terminals 20 or the semiconductor unit 40, and is not limited to the methods exemplified above. For example, a configuration in which the first connection portion 61 is joined to the connection terminal 20 by a joining technique such as laser welding, or a configuration in which the second connection portion 62 is joined to the semiconductor unit 40 by a joining technique such as laser welding, is also conceivable.

[0046] B: Second embodiment A second embodiment of the present disclosure will be described. Note that, for elements in the following exemplary aspects that have the same functions as those in the first embodiment, the same reference numerals as those in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

[0047] Fig. 6 is a perspective view of a connection lead 60c according to the second embodiment. As illustrated in Fig. 6, a plurality of notches 65 are formed on each side (631, 632) of the coupling portion 63 of the connection lead 60c according to the second embodiment. The plurality of notches 65 are slits for reducing the rigidity of the connection lead 60c, and are formed linearly along the Y direction. The side 631 is an edge of the coupling portion 63 located in the Y1 direction, and the side 632 is an edge of the coupling portion 63 located in the Y2 direction. The plurality of notches 65 are formed along the side 631 at intervals from one another, and the plurality of notches 65 are formed along the side 632 at intervals from one another.

[0048] Although the above description has focused on the connection lead 60c for the sake of convenience, the configuration in which the plurality of notches 65 are formed on the edge may also be applied to the connection lead 60a and the connection lead 60b in the same manner.

[0049] The configuration of the semiconductor module 100 is the same as that of the first embodiment except for the notch 65. Therefore, the second embodiment also achieves the same effects as the first embodiment. Furthermore, in the second embodiment, the notch 65 formed on the side edges (631, 632) of the coupling portion 63 reduces the rigidity of the coupling portion 63, so the coupling portion 63 is more likely to deform than in a configuration in which the notch 65 is not formed. Therefore, the connection lead 60 can effectively absorb stress.

[0050] C: Modified Example Specific modified embodiments that can be added to the above-described exemplary embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate to the extent that they are not inconsistent. Note that, for convenience, the following description focuses on connection lead 60c, but the configuration exemplified for connection lead 60c also applies to connection leads 60a and 60b.

[0051] (1) In the above-described embodiments, the connection lead 60 has a constant width (dimension in the Y direction) throughout the entire connection lead 60 from the first connection portion 61 to the second connection portion 62. However, the width may vary depending on the portion of the connection lead 60. For example, the width of the linking portion 63 may be different from the widths of the first connection portion 61 and the second connection portion 62. Specifically, as illustrated in FIGS. 7 and 8, a configuration is envisioned in which the width of the linking portion 63 is smaller than the widths of the first connection portion 61 and the second connection portion 62. FIG. 7 illustrates a configuration in which the central portions of the first connection portion 61 and the second connection portion 62 are connected by the linking portion 63. FIG. 8 illustrates a configuration in which the end portions (end portions in the Y1 direction) of the first connection portion 61 and the second connection portion 62 are connected by the linking portion 63. Furthermore, as illustrated in FIG. 9, a configuration in which the width of the second connecting portion 62 is smaller than the width of the first connecting portion 61 may also be employed.

[0052] (2) In the second embodiment, the linear notch 65 extending along the Y direction is illustrated, but the shape of the notch 65 may be changed as desired. For example, as illustrated in FIG. 10 , a triangular notch 65 may be formed on the side of the connection lead 60.

[0053] (3) In the above-described embodiments, the first connection portion 61 has a plurality of recesses 64 formed therein. However, the recesses 64 may be omitted. For example, as illustrated in FIG. 11 , the edge 612 of the first connection portion 61 may be continuous in a straight line. That is, the first connection portion 61 may have a simple rectangular shape in plan view. In the first embodiment, the recesses 64 are formed in the first connection portion 61, thereby reducing the heat capacity of the first connection portion 61. Therefore, compared to a configuration in which the recesses 64 are not formed in the first connection portion 61 (e.g., the configuration of FIG. 11 ), the first connection portion 61 is heated more efficiently in the holding step P2 and the transporting step P3. Therefore, the first connection portion 61 and each connection terminal 20 can be joined more efficiently by heating.

[0054] (4) In the above-described embodiments, the connecting portion 63 is a plate-like portion that spans the first connecting portion 61 and the second connecting portion 62. However, the specific shape of the connecting portion 63 is not limited to the above examples and may be changed as desired. For example, as illustrated in FIG. 12, the connecting portion 63 may be composed of an inclined portion 63a and an inclined portion 63b that are inclined in opposite directions. The inclined portion 63a is a plate-like portion that inclines in the X1 direction toward the second connecting portion 62, and the inclined portion 63b is a plate-like portion that inclines in the X2 direction toward the second connecting portion 62. As illustrated in FIG. 13, the connecting portion 63 may include a portion in which multiple pairs of the inclined portions 63a and the inclined portions 63b are connected. Furthermore, as illustrated in FIG. 14, the connecting portion 63 may include an arc-shaped portion (i.e., a portion with a semicircular cross section) centered on an axis parallel to the Y direction.

[0055] As can be understood from the above examples, the connecting portion 63 is comprehensively expressed as an element including a portion that is inclined with respect to the plate thickness direction (Z direction) of the mounting substrate 41. It is not important in the present disclosure whether the entire connecting portion 63 is inclined with respect to the Z direction or only a portion of it is inclined, and whether the portion that is inclined with respect to the Z direction is flat or curved.

[0056] (5) In the above-described embodiments, the second connection portion 62 of the connection lead 60 is bonded to the conductive pattern 44 of the semiconductor unit 40. However, the bonding destination of the second connection portion 62 is not limited to the conductive pattern 44. For example, the second connection portion 62 may be bonded to the main electrode E of the semiconductor chip 45. As described above, the bonding destination of the connection lead 60 (specifically, the second connection portion 62) is collectively expressed as the semiconductor unit 40. In other words, the configuration in which the second connection portion 62 is bonded to the semiconductor unit 40 encompasses a configuration in which the second connection portion 62 is bonded to the conductive pattern 44 and a configuration in which the second connection portion 62 is bonded to the semiconductor chip 45.

[0057] In addition, the configuration in which the second connection portion 62 is bonded to the conductive pattern 44 prevents stress from the connection leads 60 from being directly transmitted to the semiconductor chip 45, compared to a configuration in which the second connection portion 62 is bonded to the semiconductor chip 45. This has the advantage of being able to suppress damage to the semiconductor chip 45 caused by stress from the connection leads 60.

[0058] (6) In the above-described embodiments, an RC-IGBT including an IGBT and an FWD (Free Wheeling Diode) is exemplified as the semiconductor chip 45, but the configuration of the semiconductor chip 45 is not limited to the above examples. For example, the IGBT and the FWD may be mounted on the mounting substrate 41 as separate semiconductor chips 45. Furthermore, the IGBT may be replaced with a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) whose semiconductor layer is formed of silicon (Si) or silicon carbide (SiC).

[0059] (7) The term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantive meaning. Therefore, there is no room for restrictive interpretation of the position or order of each element based on the term "nth."

[0060] D: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0061] A semiconductor module according to one aspect (aspect 1) of the present disclosure comprises a semiconductor unit including a mounting substrate and a semiconductor chip mounted on the mounting substrate, a housing case for housing the semiconductor unit, a plurality of connection terminals mounted on the housing case, and connection leads for electrically connecting the semiconductor unit and the plurality of connection terminals, wherein the connection leads are made of a conductive plate material and include a first connection portion joined to the plurality of connection terminals, a second connection portion joined to the semiconductor unit at a position lower than the first connection portion in the thickness direction of the mounting substrate, and a connecting portion for connecting the first connection portion and the second connection portion, and the connecting portion includes a portion inclined with respect to the thickness direction.

[0062] In the above-described embodiments, the semiconductor unit and the plurality of connection terminals are electrically connected using connection leads made of a conductive plate material, rather than using bonding wires for each connection terminal. With this configuration, the cross-sectional area of ​​the current path is sufficiently secured compared to a configuration using bonding wires, so that the electrical resistance between the semiconductor unit and the plurality of connection terminals is reduced, and as a result, heat generation can be suppressed. Furthermore, the connecting portions of the connection leads include portions that are inclined relative to the thickness direction of the mounting substrate, and therefore elastically deform relative to the first and second connecting portions. That is, stress caused by variations in the distance between the semiconductor unit and the multiple connecting terminals is absorbed by the elastic deformation of the connection leads. This makes it possible to suppress stress concentration at the joints between the first connecting portion and each connecting terminal, or at the joints between the second connecting portion and the semiconductor unit.

[0063] In a specific example (Aspect 2) of Aspect 1, the first connection portion and the second connection portion include portions facing each other in the plate thickness direction, and the linking portion is a plate-like portion that spans an edge of the first connection portion that is located in a first direction in a plan view and an edge of the second connection portion that is located in a second direction opposite the first direction in a plan view. According to the above aspect, the distance between the first connection portion and the second connection portion in the plate thickness direction of the mounting substrate and the distance between the first connection portion and the second connection portion in the in-plane direction of the mounting substrate change due to elastic deformation of the connection lead. Therefore, the connection lead can absorb both stresses caused by fluctuations in the distance between the semiconductor unit and each connection terminal in the plate thickness direction and stresses caused by fluctuations in the distance between the semiconductor unit and each connection terminal in the in-plane direction. Furthermore, the first connection portion and the second connection portion include portions facing each other, and opposite edges of the first connection portion and the second connection portion are linked by a linking portion. Therefore, the planar space required for installing the connection lead can be reduced.

[0064] In a specific example (Aspect 3) of Aspect 1 or Aspect 2, the mounting substrate includes an insulating substrate and a conductive pattern disposed on the insulating substrate, and the second connection portion is bonded to the conductive pattern. In the above aspect, the second connection portion is bonded to the conductive pattern on the mounting substrate rather than to the semiconductor chip. This prevents stress from the connection leads from being directly transmitted to the semiconductor chip, thereby suppressing damage to the semiconductor chip due to stress from the connection leads.

[0065] In a specific example (Aspect 4) of any of Aspects 1 to 3, the first connection portion has recesses formed in a gap between two adjacent connection terminals of the plurality of connection terminals, the recesses overlapping in a plan view. According to the above aspect, the heat capacity of the first connection portion is reduced by forming the recesses in the first connection portion, and therefore the first connection portion and each connection terminal can be efficiently joined by heating.

[0066] In a specific example (Aspect 5) of any of Aspects 1 to 4, the first connection portion and the plurality of connection terminals are joined by solder, and the second connection portion and the semiconductor unit are joined by solder. According to the above aspects, the first connection portion and each connection terminal, and the second connection portion and the semiconductor unit can be easily joined by solder. For example, the temperature required for joining can be reduced compared to joining by melting connection leads (e.g., laser welding).

[0067] In a specific example (Aspect 6) of any of Aspects 1 to 5, a notch is formed on the side of the connecting portion to reduce rigidity. According to the above aspect, the notch formed on the side of the connecting portion reduces the rigidity of the connecting portion, so the connecting portion is more easily deformed than in a configuration in which no notch is formed. Therefore, the connection lead can effectively achieve the function of absorbing stress.

[0068] In a specific example (Aspect 7) of any of Aspects 1 to 6, the case includes a sidewall and a protrusion protruding inward from an inner wall surface of the sidewall, each of the plurality of connection terminals includes a first portion located on an upper surface of the protrusion and a second portion that passes through the interior of the sidewall from the first portion and has an end protruding from the top surface of the sidewall, and the first connection portion is joined to the first portion of each of the plurality of connection terminals. According to the above aspect, the first portion of each connection terminal is placed on the upper surface of the protrusion, so that the first connection portion of the connection lead joined to the first portion can be effectively supported by the protrusion. [Explanation of symbols]

[0069] 100...semiconductor module, 10...accommodating case, 11...side wall portion, 12...protruding portion, 13...installation hole, 14...terminal surface, 15...top surface, 20...connection terminal, 20a, 20c...power terminal, 20b...output terminal, 21...first portion, 22...second portion, 30...heat sink, 40...semiconductor unit, 41...mounting board, 42...insulating board, 43...metal layer, 44, 44a, 44b, 44c...conductive pattern, 45, 45a, 45b...semiconductor chip, 50...connecting wire, 60, 60a, 60b, 60c...connecting lead, 61...first connecting portion, 62...second connecting portion, 63...connecting portion, 64...recess, 65...notch portion.

Claims

1. a semiconductor unit including a mounting substrate and a semiconductor chip mounted on the mounting substrate; a housing case for housing the semiconductor unit; a plurality of connection terminals disposed in the housing case; connection leads that electrically connect the semiconductor unit and the plurality of connection terminals; Equipped with the connection lead is made of a conductive plate material, a first connection portion joined to the plurality of connection terminals; a second connection portion joined to the semiconductor unit at a position lower than the first connection portion in a thickness direction of the mounting substrate; a connecting portion that connects the first connecting portion and the second connecting portion, The connecting portion includes a portion inclined with respect to the plate thickness direction. Semiconductor module.

2. the first connection portion and the second connection portion include portions facing each other in the plate thickness direction, The connecting portion is a plate-like portion that spans an edge of the first connecting portion that is positioned in a first direction in a plan view and an edge of the second connecting portion that is positioned in a second direction opposite to the first direction in a plan view. The semiconductor module of claim 1.

3. The mounting board is an insulating substrate; a conductive pattern disposed on the insulating substrate; The second connection portion is joined to the conductive pattern. The semiconductor module of claim 1.

4. The first connection portion has recesses formed therein that overlap in a plan view with a gap between two adjacent connection terminals among the plurality of connection terminals. The semiconductor module of claim 1.

5. the first connection portion and the plurality of connection terminals are joined by solder; The second connection portion and the semiconductor unit are joined by soldering. The semiconductor module of claim 1.

6. A notch is formed on the side of the connecting portion to reduce rigidity. The semiconductor module of claim 1.

7. The storage case is A side wall portion; a protrusion protruding inward from an inner wall surface of the side wall portion, Each of the plurality of connection terminals is a first portion disposed on an upper surface of the protrusion; a second portion that passes from the first portion through the inside of the side wall portion and has an end that protrudes from the top surface of the side wall portion, The first connection portion is joined to the first portion of each of the plurality of connection terminals. The semiconductor module of claim 1.

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